Internal combustion engines such as, for example, diesel engines, gasoline engines, and gaseous fuel powered engines are supplied with a mixture of air and fuel for subsequent combustion within the engine that generates a mechanical power output. In order to maximize the power generated by this combustion process and reduce levels of resultant pollutants, the engine is often equipped with a turbocharged air induction system that implements exhaust gas recirculation (EGR).
A turbocharged air induction system includes a turbocharger that uses exhaust from the engine to compress air flowing into the engine, thereby forcing more air into a combustion chamber of the engine than the engine could otherwise draw into the combustion chamber. This increased supply of air allows for increased fueling, resulting in an increased power output. A turbocharged engine typically produces more power than the same engine without turbocharging.
EGR systems recirculate exhaust gas by-products into the intake air supply of the internal combustion engine. The exhaust gas, which is redirected to the combustion chamber of the engine, reduces the concentration of oxygen therein, thereby lowering the maximum combustion temperature. The lowered maximum combustion temperature slows the chemical reaction of the combustion process, thereby decreasing the formation of nitrous oxides. In addition, the particulate matter entrained in the exhaust is burned upon reintroduction into the engine combustion chamber to further reduce the exhaust gas by-products.
Control of the EGR system is often dependent on performance of the turbocharger. In particular, in order to provide the correct flow ratio of exhaust gas to intake air that results in compliance with emission regulations while maintaining temperatures with the induction system that provide for extended component life of the internal combustion engine, it may be important to continuously monitor, estimate, or otherwise calculate operational characteristics of the turbocharger during operation of the turbocharger. One method of estimating a turbocharger's performance is described in U.S. Pat. No. 6,401,457 (the '457 patent) issued to Wang et al. on Jun. 11, 2002. The '457 patent describes a system and method for estimating a compressor's efficiency and outlet temperature. The system of the '457 patent includes a compressor inlet temperature sensor, a compressor inlet pressure sensor, a fresh mass air flow sensor, a turbo speed sensor, an intake manifold pressure sensor, an EGR differential pressure sensor, an EGR valve position sensor, an exhaust pressure sensor, and an intake manifold temperature sensor. The method includes estimating the volumetric efficiency of the compressor based on a measured engine speed, measured intake manifold temperature, measured intake manifold temperature pressure, and measured exhaust pressure. The method then includes estimating a charge flow value as a function of the estimated volumetric efficiency, the measured engine speed, and the measured intake manifold temperature and pressure. A map is then used to select EGR mass flow based on a measured pressure differential and the measured inlet manifold pressure. A mass flow value is estimated based on the estimated charge flow value and the estimated EGR mass flow. A corrected mass flow value is calculated as a function of the mass flow value and the measured compressor inlet temperature and pressure. A corrected turbo speed is calculated as a function of the measured turbo speed and the compressor inlet temperature. A compressor pressure ratio is calculated as a function of the corrected mass flow value and the corrected turbo speed. The outlet temperature of the compressor is estimated based on the measured compressor inlet temperature, the estimated volumetric efficiency, and the calculated compressor pressure ratio. Alternatively, a compressor temperature ratio may be calculated based on the measured compressor inlet temperature, corrected mass flow value, and the corrected turbo speed; based on the measured compressor inlet temperature, corrected turbo speed, and calculated compressor pressure ratio; or based on the measured compressor inlet temperature, the calculated compressor ratio, and the corrected mass flow value.
Although the system of the '457 patent may provide ways to sufficiently estimate the pressure ratio, efficiency, and outlet temperature of a compressor, it may be expensive and unreliable. In particular, because of the number of sensory inputs, the cost of system may be substantial. In addition, because the outputs of the system rely on the large number of sensory inputs, a failure of one of the sensory inputs could produce unreliable estimations.
The control system of the present disclosure solves one or more of the problems set forth above.